Chapter 17 Study Guide Flashcards
What are the four principal mechanisms of communication between cells? Describe them
1) Gap junctions: Allow molecules, nutrients, and electrolytes to move from cell to cell
2) Neurotransmitters: Released from presynaptic neurons to postsynaptic neurons
3) Paracrines: Secreted into tissue fluids to affect nearby cells
4) Hormones: Chemical messengers that travel in the bloodstream to other tissues and organs
The endocrine system consists of glands, tissues and cells that secrete what? Define endocrinology
1) Hormones
2) Endocrinology: the study of the endocrine system and the diagnosis and treatment of its disorders
What properties does a hormone have? (3)
What are some endocrine glands?
1) Properties:
a) They’re chemical messengers
b) They’re transported by the bloodstream.
c) They stimulate physiological responses in target cells
2) Examples of endocrine glands include the thyroid, pituitary gland, hypothalamus, and pancreas.
How do exocrine and endocrine glands secrete their products? Which has external secretions; which have internal secretions?
1) Exocrine glands use ducts, endocrine glands do not.
2) Exocrine glands have external secretions, whereas endocrine glands have internal secretions.
What are examples of exocrine secretions? What are examples of endocrine secretions?
1) Examples of exocrine secretions include sweat, tears, digestive juices, and saliva
2) Examples of endocrine secretions include the secretion of hormones (ADH, FSH, OT, ACTH, GH, etc)
1) In comparing the nervous system to the endocrine system, what is something they have in common regarding specificity, receptors, and communication?
2) Both neurotransmitters and hormones depend on target cells to provide what?
1) Both rely on their targets having receptors, both serve for internal communication, several chemicals act as both hormones and neurotransmitters, and both systems can have a similar effect on target cells.
2) The targets of the nervous and endocrine systems (the postsynaptic neuron and target organ/cells respectively) both must have receptors.
1) In comparing the nervous system to the endocrine system, what is different regarding speed and persistence of response
2) How are they similar in adaptation to long-term stimuli and area of effect?
3) Is one more focused on a particular organ or limited number of cells or does one have a more widespread effect?
1) The nervous system has a quicker but more short-lived response than the endocrine system; it may take the endocrine system seconds or days to respond, but the effect can last for days or longer.
2) The nervous system adapts quickly to long-term stimuli and the response declines, whereas the endocrine system adapts more slowly and response persists.
3) The nervous system is targeted and specific (one organ) whereas the endocrine system is general and widespread (many organs)
1) Give 3 examples of chemicals that function both as neurotransmitters and hormones.
2) Some hormones and neurotransmitters produce identical effects on the same targets, can you think of an example?
1) Norepinephrine, dopamine, and ADH
2) Norepinephrine and glucagon both cause glycogen hydrolysis in liver
1) How does the nervous and endocrine systems regulate each other?
1) Neurotransmitters can affect glands, and hormones can affect neurons
1) Where is the location of the hypothalamus?
2) List some of the primitive functions it regulates.
3) How is the pituitary gland connected to the hypothalamus, what is the name of the stalk?
4) The pituitary gland is housed in a depression of which bone and its bone marking?
1) The hypothalamus is above the pituitary gland in the brain
2) Water balance, thermoregulation, sex drive, childbirth
3) The pituitary gland is connected by the stalk called the infundibulum.
4) The pituitary gland is housed in the sella turcica of the sphenoid bone.
Which structure of the pituitary has no nervous connection to the hypothalamus? How is it linked to it then?
The anterior pituitary is connected to the hypothalamus by the hypophyseal portal system.
What does the hypophyseal portal system consist of, and where are these things located?
The primary capillary bed in the hypothalamus and the secondary capillary bed in the anterior pituitary.
How many hormones (by number) are released by the hypothalamus that regulate the anterior pituitary? Of that number, how many stimulate release and how many inhibit release?
6 hormones; 4 stimulate and 2 inhibit (PIH and somatostatin)
1) Can you list the 6 hormones released by the anterior pituitary?
2) Can you list the 6 hypothalamic hormones that control the hormones released from the anterior pituitary?
1) FSH, LH, ACTH, TSH (FLAT) are the tropic hormones; PRL and GH (PiG) are non-tropic.
2) TRH, CRH, GnRH, and GHRH promote secretion; PIH and somatostatin inhibit.
1) The posterior pituitary constitutes the posterior one-quarter of the pituitary. How does the hypothalamus connect with it?
2) What are the names of the two hormones stored here?
3) What causes the hormones stored in the posterior pituitary to be released?
1) The hypothalamo-hypophyseal tract (nerves).
2) ADH and OT are stored in the posterior pituitary.
3) They’re released by an action potential moving down the nerve
1) In summary, how many total hormones are released by the hypothalamus?
2) How many regulate the anterior pituitary?
3) Of the hormones in the posterior pituitary, how many were produced by the posterior pituitary?
1) There are 8 hypothalamic hormones
2) 6 regulate the anterior pituitary.
3) Neither of the 2 hormones stored in the posterior pituitary were produced there.
1) What does FSH target?
2) What does LH stimulate in females? In males?
3) What hypothalamic hormone stimulates release of FSH and LH?
1) The gonads
2) In females it stimulates ovulation, stimulates corpus luteum to secrete progesterone. In males it stimulates testes to secrete testosterone
3) GnRH releases FSH and LH
1) TSH stands for what?
2) What organ does TSH target, and what hormone is stimulated to be released?
3) What hypothalamic hormone stimulates release of TSH; what hypothalamic hormone inhibits release of TSH?
1) Thyroid stimulating hormone.
2) Targets the thyroid to release thyroid hormone.
3) TRH stimulates the release of TSH, somatostatin inhibits the release of TSH.
1) ACTH stands for what?
2) What specific part of an organ does ACTH target, and what hormone is stimulated to be released?
3) What hypothalamic hormone stimulates release of ACTH?
1)Adrenocorticotropic hormone
2) It stimulates the adrenal cortex to secrete glucocorticoid.
3) Corticotropin-releasing hormone (CRH) stimulates its release.
1) What does PRL stand for?
2) What organ does PRL target, and what is stimulated to be released?
3) What hypothalamic hormone stimulates release of PRL; what hypothalamic hormone inhibits release of PRL?
1) PRL stands for prolactin.
2) Targets the mammary glands to produce milk.
3) TRH promotes the release of PRL; PIH inhibits the release of PRL.
1) What does GH stand for?
2) What does GH do?
3) What hypothalamic hormone stimulates release of GH; what hypothalamic hormone inhibits release of GH? Note that the hypothalamic hormone that inhibits release of GH, is the same that inhibits release of what other anterior pituitary hormone?
1) GH stands for growth hormone,
2) It primarily stimulates mitosis and cellular division; this increases blood glucose, lipid metabolism, and blood glucose levels.
3) GHRH stimulates its release and somatostatin inhibits its release (also inhibits the release of TSH).
1) What does ADH do? (hint… kidneys)?
2) Why is it also called vasopressin?
3) Hyposecretion results in what disorder? What is the classic symptom?
1) It increases water retention by the kidneys.
2) It’s also called vasopressin because it can cause vasoconstriction.
3) Diabetes insipidus, and its classic symptom is polyuria.
Oxytocin (OT) has a variety of reproductive functions ranging from intercourse to birth to breast-feeding. Can you give some examples of its functions?
1) A surge of OT is released during sexual arousal and orgasm; promotes feelings of sexual satisfaction and emotional bonding between partners. 2) Stimulates labor contractions during childbirth and stimulates flow of milk during lactation (both positive feedback mechanisms); may promote emotional bonding between lactating mother and infant
1) In times of stress, this triggers ACTH secretion, what does this lead to? 2) During pregnancy, this induces prolactin secretion. What does this do?
3) High osmolarity triggers release of ADH. What does this do?
4) Infant suckling triggers release of OT, which does what?
5) What organ controls rate of pituitary hormone secretions?
1) Stimulates adrenal cortex to secrete glucocorticoids
2) Causes the mammary glands to grow.
3) Increases fluid retention by the kidneys; decreases osmolarity
4) Stimulates flow of milk
5) The hypothalamus (and cerebral control)
1) Define negative feedback.
2) Using the pituitary–thyroid system, how would negative feedback inhibition occur? 3) Can you think of an example of where a hormone triggers a positive feedback cycle?
1) Negative feedback: increased target organ hormone levels inhibit release of hypothalamic and/or pituitary hormones
2) Higher levels of thyroid hormone inhibits release of TRH by hypothalamus and of TSH by anterior pituitary
3) Stretching of uterus increases OT release, causes contractions, causing more stretching of uterus, etc. until delivery
1) The pineal gland is located where?
2) The pineal gland’s function is somewhat mysterious; it may play a role in establishing ____________ rhythms of physiological function.
3) During the night it synthesizes what?
1) The pineal gland is located in the brain posterior to the hypothalamus.
2) Circadian
3) At night the pineal glad synthesizes melatonin.
The thymus is located where? What organ systems does it play a role in? It’s the site of maturation for what cells?
The thymus is located just above the ascending aorta, and it plays a role in the endocrine, lymphatic, and immune systems (maturation of T cells).
1) How does the thymus change in terms of size over the course of a person’s life?
2) What does it secrete?
1) The thymus shrinks/ undergoes involution after puberty.
2) It secretes thymopoietin, thymosin, and thymulin.
1) The thyroid is located where?
2) Thyroid follicles are filled with a protein-rich colloid and lined with a simple ____________ epithelium of follicular cells.
3) What does it secrete, and in response to what stimulus from the pituitary?
1) Located in the neck at an isthmus below the larynx.
2) simple cuboidal epithelium
3) It secretes T3 and T4 (thyroid hormone) in response to TSH.
1) What is the primary effect of TH?
2) What does TH do in terms of oxygen consumption? What does it do to the respiratory rate, heart rate and strength of the heartbeat? What about the appetite?
1) The primary effect of TH is increasing metabolism.
2) It also increases oxygen consumption, heat production, appetite, growth hormone secretion, alertness, reflex speed.